Automatic train-control system.



0. A. ROSS. AUTOMATIC TRAIN CONTROL SiSTEM.

APPLICATION FILED JUNE 26. "[5. 1,263,603. PatentedApr. 23. ma

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FIG.1.

INVENTOR BY I y xfr omn Quad-M O. A. ROSS. Auwmmc mm CONIRUI. SYSTEM.

Patented Apr. 23,1918

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INVENTOR M a. M

ATTORNEY u 4 m. s? n 3 h fi A. .H WU u ON m M m .Q n N a Q a U. 0 Q Q EA II 4A. U N. w R A w i w HI u 7 h n a a um /fi no 3 h. N E n 3 m a A Evt UNITED STATES PATENT OFFICE.

OSCAR A. ROSS, OF ROCHESTER, NEW YORK, ABSIGNOR T0 GENERAL RAILWAYSIGNAL COMYANY, 0F GATES, NEW YORK, A CORPORATION OF NEW YORK.

AUTOMATIC TRAIN-CONTROL SYSTEM.

Specification of Lctteralatent.

Patented Apr. 23,1918.

Application filed June 26, 1915. Serial 110.36.535.

To all whom it may concern:

Be it known that I, Oscan A. Ross, a citizen ot' the lTnited States, anda resident of the city of Rochester, in the county of Monroe and Stateof New York, have invented a new and usefulAut-omatic Train-ControlSystcnnct' which the following is a Specilication.

This invention relates to automatic-train control systems, and moreparticularly to such systems in which the movemcut'of the train iscontrolled. in some appro riute manner. by an electrically operatedcvice located on lhc train. as a control relay, the coutrolof saiddevice being accomplished Ivy suitahleramps or other devices arrangedalong the trackway and adapted to cooper? ate with shoes or otherdevices carried by the train." a

One of the principal objects of the invention is to construct and arrane the parts of atrain control system of t e character specified so thata number of units, such as two or more locomotives or motor cars, may

be included in the same train without affecting the operation'of thetrain control system or impairing its elliciency.

A further object of the invention is to devise a simple and reliabletrain control apparatus and ramps, circuits and electrical connectionstherefor arranged along the trackway which will operate to'proporlctmtroldhd control, r( ..hiy. or other contrl ling device oneachlocomotive or motor car .lIIClUdCtllll a train, regardless ofthe'numher of locomotives or motor cars, or their position in the train.or of the length of the blocks or of the train.

Other objects and advantages will appear as the description of theinvention progresses, andt 0 novel features of the invention will beparticularly pointed out in the up )ende'd claims? lencrallj, stated,the. invention consists in providing a shorflcoutr'ol section at theentrance to caehblock section of the trackway over whichthc train passesto which is connected and 'lry which'liscontrolled suitulilc electricalappliances "so that" the condi ileil'l of the ramp or control deviceadjacent to each control section'will be maintained the some while thetrain is passing that control section.

The invention further consists in the partsand in the arrangements andcombinations of parts, more fully set forth hereinafter.

In describing the invention in detail, reference'is had to theaccompanying drawing, wherein I have illustrated a preferred physicalembodiment of my invention, and wherein like characters of referencedesignate corresponding parts throughout the several views, and inwhich:

Figure 1 is a diagrammatic illustration of a railway train and a trackfor said train, and shows the parts associated with thetrain and withthe track and the circuits and electrical connections between said partswhich embody the invention, the parts in said figure being shown intheir normal positions and in the condition existing when a trainapproaches one of the ramps located the required spacing of the trains,and for convenience in description will be hereinafter termed blocksections. The sections B and D are comparatively short and may he asshort as desired. prmiding that they are longer than the distancebetween any two successive pair of wheels. In other words. the sectionsB and D, which will he hereinafter termed control sections, are longenough so that as the train passes over them at least. one pair ofwheels of said train will at all times he. on said controlsectio'n.Although only two control sections B and 1), tho intermediate blocksection C and the adjacent ends of the two block sections A and E, areshow-11in the drawings,

' my 1:: mthe it is to be understood that the same alternate arrangementof control sections and block sections is carried out throughout thedesired length of the track, a control section being located at theentrance to each block section, as illustrated, the direction of normaltrallic being indicated by the arrow X.

Across the two track rails 1 and 2 at one end of each block section A, Cand E is connected a source of electric current, as a. battery 4; and atthe other end of each block section a track relay 7 is connected acrossthe track rails 1 and 2 by conductors 5 and 6. The parts and circuitsare the same for the control sections B and D, and the con: doctors andparts of the control section D are given the same reference character asthe corresponding parts and conductors of the control section B with adistinctive exponent 1 added thereto. These track relays 7, togetherwith the track rails 1 and 2 and the battery 4, constitute the wellknown normally closed track circuit, as will be readily understood bythose skilled in the art of railway signaling. The track relay for eachblock section is normally energized, that is, when no train occupiesthat block section, and their armaturcs will be normally held in theirupper position, as shown in the drawing.

Associated with each control section isa relay 8,- hereimiftcr termed aramp relay, which is connected by a conductor 9 to the track rail 2 andby conductors 10 and 11 to a local source of current, such as a battery12, which in turn is connected by u conductrack ruill. Adjacent to eachcontrol sect ion B and D is a contact rail or ramp R, which is supportedin any suitable way on the tics of the railway track, but is insulatedfrom said tics and from the track rails. The conductors and-electricalconnections between the different, operative parts of the control systemalone the trackway will not be described in detail sincethcsoconncctions and the different operating circuits will be fully setforth hereinafter in the description of the operation.

T no apparatus on the vehicle for controlling the mownnent tiicreof mayhe of any suitable constructlonfbut is llustrated as constructed andarranged sothnt it will not be all'eiitcd if a glifl'erencc of potentialexists between the raihiTIi-anyl the truck rail 1, but will be set intooperation to control the movement of the train in some prtrpriatcuninncr in'cnsc such difference 0 potci'itial does not exist; Therailway train isshown 'diagrummatically as coinprisiug two pairs ofwheels 14-14 and 16-1( connected by axles l5 and 17 respectivelyw'lfibh. rcprsent the wheels and axles of separate cars .or locomotivesconstituting a train. The, x'les 15 and 17 are illustrated as connectedv a bar 18 which represents the frames of the cars or locomotivesconstituting the train.

A bracket 1}) of insulatin material is suitably su ported "on thetrai-n,'fbeilig shown as mounte on the rear mile 17 and so orted on thebracket 19 is a vertically move e shoe or plunger 20, which is presseddownwardly by a spring 21. i The shoe 20 .is arranged to cooperate withthe ramps R arranged along the trackway and is designed to makeelectrical contact with said ramps and also to be raised so as tointerrupt a normal! closed circuit on the train. To accomplish t is pur-Jose, the shoe 20 may be provided with a utton 24 of insulatin materialarranged to lift a contact spring 2 out of contact with a contact member28, said button 24 also serving tolimit downward movement of the shoe20. The contact sprin 22 and the contact member 23 are suita'b y securedto the bracket 19, which being of insulating material, serves toinsulate said contact spring and said contact member from each other andfrom the frame of the vehicle.

The contact spring 22 and the contact member 23 control a normallyclosed circuit for maintaining a control relay 25 energized. Thiscontrol relay 25 has two armatures 27 and 28, one armature 27 beinginterposed in the local normal] 1 closed circuit, for saidrelily 25, andthe ot er armature 28 controlling a local normally closed circuit fora-de'vice K by means of which the movement 'of the train is controlled.This device K maybe of any suitable construction, but is illustrated asset into operation .whendciinergized and restored to its normal positionwhencnergized. This device K may be used to apply the brakes on the traminstantancously when it is operated or after a certain interval, whichmay be fixed or variable according to the speed of the train and thedistance it has traveled after said device K was set into operation.Various devices well known in the art will satisfy the requirements ofthe device K and a detail description ofsaid device will not be givenhere.

Having described generally the structure and arrangement of, the variousparts or stituting a system for automatically controlling railway trainswhich embodies theinrent ion, the operation of said system will bedescribed for diifercnt cases in which cerlain conditions,"sueh as mayoccur in praclice, are nssllliioil to exist along the trackway.

Referring to Fig. l, for the first condition to be considered, assumethat the train under consideration is m the block section A, as shown insniddigurc and is about to enter the'control section B; [that "the trainhas Found the trackway unobstructed and is running without being under,the control of the device K and that lhercis no train either in theblock section the control section D. or the block section E. Since theblock sections C and E ar'e not occu ied, the track relays 7 and 7ftherefor wil be, energizcd by current supplied from the batteries l, aswill be clearly understood by those skilled in the art; and since saidtrack relays are cnergizcd, their armaturcs 32, 33 and 32, 33 will. be.in their raised position, as shown. The ramp relay 8 for the ramp R atthe entrance to the control section B is deencrgized and its a rmatures30 and 3t are in their lower position, as shown. A difference ofpotential exists between the ramp it and the track rail 1 according tothe par tial circuit as follows: from the ramp R, comlimtor 3t,arn'iature 30 of the ramp relay H in its lower position, conductor 35,armature 52 of the track relay 7 in its upper position. conductors 36,37 and 1]. battery 12 and conductor 13 to the track rail 1.

It is noted that this first partial circuit tor maintaining a differenceof potential between the ramp R and the track rail 1 Will he ilucrruptedif a train occupies the block section but this partial circuit is in nowise rlcpcndent upon whether or not the control section I) and the blocksection E are m-cupicd. lhis condition, which exists before the firstwheels 14 and axle 15 of the train enter the control section B, may beused in cases where the construction of the device K makes it desirablethht each time a train approaches a block section the shoe of the train,should strike a ramp between which and a traclrrail a difference ofpotential should exist, provided the next block section, as (7, isunoccupied, and re gardlcss ot' whether or not the next succeeding blocksection, as E, is occupied. To obtain this result the ramp R may be madelong enough and so located with reference to the insulating joint 3 atthe entrance to the control section B that the first shoe 20 ot thetrain will make electrical contact with said ramp before the first pairof wheels hi H and their axle 15 enter the control section ll.

Another factor which determines the length and location of the ramps andwhich may he noted at this time, is that the front end of a ramp must bea greater. distance from the insulating joint 3 at the entrance to thenext block sectionlhan the distance between the last pair of wheels andaxle of the train and the last contact shoe 2t in order that the lastcontact shoe-2o will ha re discontinued electrical comm-r with the rampb the time the last pair of 'whe'els'andaxlc leav'c the control section1 When the lirst pair of"i\"hi-.cls H-'-l-l and axle ii": of thetrain'cnter the control s ction 1 the ramp relay 8 of'said controlsection is energized according-{to the lollo\\'itn circuit: battery l'2,eondnctors ll and I0, re in 8. conductor 9, track iail 2, wheels 14,

the axle 1.), track rail 1 and conductor 13 back was battery, 12. whimtheti icjis conductor 4,4, contact member 23, contact cnergized itsarmature is. raised, t reby interrupting the first partial circuithereinbefore traced which normally maintains a difference of potentialbetween the ramp R and the track rail 1. However, under the conditionsassumed the control section I) is unoccupied and the armatures 3t) and31 of the relay 8 of the control section D are in their lower position,as shown; and since the block section E is unoccupied, the arniatures 32and 33 of its track relay 7" are in their upper position, as shown.onsequently. when the armature 30 of the relay 8 ofthe control section Bis raised, asecond partial circuit for maintaining a difference ofpotential between the ram) R and the track rail 1 is established asollow's: from the ramp R, conductor 34, armature 30 ot the relay 8 inits up )(l' position, conductor 38. arn'iaturc 31 of the relay 8 in itslower position, conductor 35), armature 33 of the track relay 7 in itsupper position, conductors 37" and 11, battery 12, conductor 13 to thetrack rail '1. It is noted that this lastmentionod second, partial cuitis interrupted if the control section I) or the block section E areoccupied by a train. but is not affected by the presence of a train inthe block section C, and the result is that, as the wheels of the trainenter the block section (7 and cause the'track' relay, 7

thereof to be dciinergizial, this last-incritioned partial circuit willnot be interrupted; but will be maintained untilthe last .pair of wheelsand axle of the train have left the control section B.

Whenthe shoe 20 engages the ramp R the contact spring 22 and the contactm'e nbcr 23 is broken, thereby interrupting the following normallyclosed circuit through the control relay 25: from the battery 26,

spring 2:2, conductor 45, armature 27 of the control relay 25 in itsupper position, conductors ltt and 47, control relay 25 and condoctors48 and 49 back to the battery 26, Also, as soon as the shoe 20 makeselectrical contact with the ramp R and shortl before the contact spring22 is separated rein the contact; member 23, current will be supplied tothe control relay 25 from the ramp R according to the following circuit:from the battery 12, conductors 11, 37', and 4t), armature 33 of thetrack relay 7 in its upper position, conductor 3!), armature It! of theramp relay 8' in its lower position, conductor 38, armature 30 of theramp relay 8 in'its'upper position, conductor 34, ramp R. sho'etQt),conductors titland 48. control relay 25, mnductors 4-7 and 51 to theflgime 18 iii" the trai'n, and thence throuti'hftlhc wheels; and axle tothe track rail 1 and along conductor 13 back to the battery 12. In

it is raised and electrical contact between v block section E.

this way, each time the shoe 20 engages a ramp the control relay 25 willbe kept energized and the vehicle may proceed safely, providing adili'erence of potential exists between that ramp and a track rail.

For the next condition to be considered, assume that the train is in theblock section A and about to enter the control section B; that saidtrain has found the track unobstructed and is running without beingunder the dominance of the train control device K; and that there is notrain in the block section C, but there is a train in the In this casethe track relay 'i' of the block section E will be denergized by thepresence of the train in said 1 block section, as will be understood bythose skilled in the art, and the armature 33 of said truck relay willbe in its lower position, thereby interrupting the second partialcircall; for maintaining '1 difference of potential between the ramp Rand the track rail 1 as the train proceeds through the control section Band into the block section C. The first partial circuit which normallymaintains a difference of potential between the ramp R and the trackrail 1, however, will not be affected by the presence of the train inthe block section E, as pointed out hereinbefore, so that the control.relay 25 on the train will be energized if a. shoe 20 of said trainstrikes the. ramp R before the firstair of wheels and axle of the trainenter t e control section B; and then subsequently, when said first pairof wheels and axle enter the control section B, the control relay 25will be deenergized.

When the control relay 25 is deenergized its armature 27 drops andinterrupts the normally closed circuit from the battery 26 through thecontrol relay 25 so that after the shoe 20 leaves contact with the rampR and the contact spring 22 makes electrical contact with the contactmember 23, the control relay 25 will remain deia'nergized. Also, whenthe control relay 25 is deenergized, its armature 28 drops andinterrupts the following normally closed circuit through the controldevice K: from the battery 29, con doctor 52, control device K,conductor 53, armature 28 in its upper position and conductor 54 back tothe battery 29. In this way, when the train occupies the block sectionE, the control device K will be set into operation, and may operate toapply the brakes automatically or may be used to set any suitable traincontrol apparatus of some other description into operation. The sameresult is produced in case the control section I) is occupied, as by asingle locomotive or motor car, since in this case the ramp relay 8 ofsaid control section D will be energized and its armature 31 raised tointerrupt the secondpartial circuit for mamtaining a difference ofpotential between the ramp R and the contact ramp 1.

For the next condition to be considered, assume that the train is in theblock section A and is about to enter the control section B, and thatthe block section C is occupied. In this case the train before itentered the block section A would have been placed under the dominanceof the control device K, since the presence of a train in the block 0would have set the control apparatus K into operation at the entrance tothe block section A. in the same way as the presence of a train in theblock section E causes the control device K to be set into operationwhen the train entered the block section C,

as hereinbefore explained. The presence of the train in the blocksection 0 requires that the train in the block section A must eitherstop before it enters the block section C or must proceed with greatcaution and at a low speed under the dominance of the train controlapparatus; and, consequently, to acconiplish this result, no differenceof potential should exist between the "ramp R and the track rail 1. inorder that the following train will not be released from the dominanceof its train control apparatus. This absence of any difference ofpotential between the ramp R and the track rail 1 is efi'ected by reasonof the fact that the presence of a train on the block section 0 causesthe dei nergization of the track relay 7, with the result that itsarmature 33 drops and interrupts the first partial circuit, hereinbeforeset forth, which normally maintains a ditl'erence of potential betweenthe ramp it and the track rail 1.

The modified arrangement of circuits shown in Fig. 2 is substantiallythe same as the arrangement of circuits in Fig. 1, except that the ramprelays 5-) in Figv 2 are arranged on a normally closed circuit, insteadof on a normally opcn'circuit as in Fig. 1. Each control section B and Dis provided with a track battery 59 connected across the track rails 1and 2 and the ramp relay 55 is connected by wires 56, I? and it; crossthe track rails 1 and without. however. a battery being included in saidwires. as is the case in Fig. 1. In this arrangclnentof circuits theramp relay 55 is normally energized from the track battery 59 and whena, pair of wheels and axle en tor the control section B the battery 59is shunted to dci nergize the relay 55. Because of this change from anormally open to a norlnally c'loscdcircuit, the contacts o thearmaturesol the ramp relay 55') are re versed, will be clearlyunderstood by those skilled" in the art. A further dill'ercnce betweenFig. 2 and Fig. 1 is tha the battery 6-1 for establishing a dill'ercnceof potential between the ramp R and the track rail 1 is interposed inthe conductor between said ramp and the armature 60 of the ramp relay55, In other respects, the parts and their electrical connections arethe same in Fig. 2 as in Fig. 1.

Without entering into a detail description of the operation of themodified arrangement of circuits shown in Fig. 2, the first partialcircuit for normally maintaining a difference of potential between theramp R and the track rail 1 is traced as follows: from the ramp R.conductor 65, battery 64, conductor 66, armature 60 of the ramp 55 inits upper position, conductor 67, armature 62 of the track relay 7 inits upper position, conductors 68, 69 and 57 to the track rail 1. Whenthe control section D and the block section E are not occu ied and thefirst pair of wheels and axle o the trainv enter the control section B,the second partial circuit for maintaining a difference of potentialbetween the ramp R and the track rail 1 is as follows: from the ramp R,conductor 65, battery 64, conductor 66, armature 60 of the ram relay 55in its lower position, conductor 0, armature 61 of the ramp relay 55 inits upper position, conductor 71 armature 63 of the track relay 7 in itsupper position, conductors 72 69 and 57 to the track rail 1. Theoperation of the modified arrangement of circuits shown in Fig. 2 fordifierent conditions will be obvious b comparison with the similar 0oration o the arrangement of circuits 5 own in Fig. 1; and a detaildescription will not be given.

Although I have particularly described the construction of one physicalembodimont of my invention, and ex lained the operation and principlethereo nevertheless, I desire to have it understood that the formselected is merel illustrative, but does not cxhaust'the possiblephysical embodiment of the idea of means underlying my invention.

What I claim as new and desire to secure by Letters Patent of theUnited. States, is:

1. In an automatic train control 5 stem, in combination: a railwaytrackway a apted for fnovin vehicles and comprising electrically isoated block sections, a comparatively short control section at theentrance to each of said block sections and electrically isolatedtherefrom, an insulated ramp positioned near the entrance to each ofsaid block sections-1 a ramp relay as ciated with each 'control sectionand centre led by the presence of a; train on the corresponding sectionfor creating a difi'crencc of potential between each of said ramps and atrack rail.

2. In an automatic train c itrol system, in combination: a railway tra(way adapted for moving vehicles and comprising electrically isolatedblock sections, a comparatively short control. sectitm at the entranceto each of said block sections and electrically isolated. therefrom, anihsulatcal rump positioned near the entrance to each of said blocksections, a ramp relay associated with each control section andcontrolled by the presence of a train on the corresponding controlsection, a source of electric current and a track relay associated witheach block section and constituting a normally closed track circuit, apartial circuit controlled by the corresponding ramp relay and the trackrelay of the next succeeding block section for creating a difference ofpotential between each of said ramps and a track rail, and anotherpartial circuit for creating a diflerenee of potential between said rampand a track rail which is controlled by the ramp relay of the nextsucceeding control section and the track relay of the second succeedingblock section. v

3. In an automatic train control system, in combination: a railwaytrackway adapted for moving vehicles and comprising electricallyisolated block sections, a comparatively short control section at theentrance to each of said block sections and electrically isolatedtherefrom, an insulated ramp positioned near the entrance to each ofsaid block sections, a source of electric current and a track relay foreach blocksection constitutin a normally closed track circuit, each ofsaid track relays having a pair of cooperating contacts which are closedwhen said re ay is energized, a relay associated with each ramp, acircuit for each ramp relay connected across the track rails of the corresponding control section and including a source of electric current,said ramp relays being energized when the wheels of a tram are on saidcontrol sections, circuit. controllers operated by said ramp relaysandtwo partial circuits for each ramp arranged in multiple and in serieswith a source ofcurrent, said partial circuits creating a difference ofotential between said ramp and a track rail, one of said partialcircuits being closed when the ramp relay of the correspondim ramp isdeiiner'gized and the track relay or the next "succeeding block sectionis ener ized, and tlsfeother partial circuit bein c osed when said ramprelay is energize and the track relay of the second succeeding' blocksection is energized.

4. Inan automatic train control s stem, in combination: arailwaytrackway a apted for moving vehicles and comprising electricallisolated block sections, a comparative y short control section at theentrance to each of said block sections and electrically isolatedtherefrom, an insulated ramp ositioned near the entrance to each of saidiilock sections, circuit controlling devices associated with eachcontrol section, a circuit controlling device associated with each locksection, a partial circuit associated with each ramp for creating adifl'erenoe of potential between that ramp and a track rail; saidpartial circuit being controlled by the responding control section andthe block section next ahead and being interrupted when either saidcontrol section or said block section is occupied by a train, andanother partial circuit associated with each ramp and in multiple withsaid first-mew tioned partial circult for creating a difl'erence ofpotential between said ramp and a track rail, said second partialcircuit being controlled by the circuit controlling devices of thecontrol section next ahead and the second block section ahead and beinginterrupted when either said control section ahead on said second blocksection-ahead is occu ied. p

5. n an automatic train control system, in combination: a track dividedinto track circuit block sections and comparatively short controlsection'sone at the entrance to each block section; an impulse deviceassociated with each block section; control circuits for each impulsedevice governed respectively by the track circuit of the corresponding"block section and the trackcircuit of the block section next inadvance; and means associated with each control section and responsiveto the presence of a train thereon for selectively controlling theconnection between the device and its controlling circuits.

6. In an automatic train control in combination: a track divided intotrack circuit block sections and comparatively short control sectionsone at the entrance to each block section; an impulse device associatedwith each block section; 'a relay and asource of current connected toeach control sectionand constituting means for detecting the presence.of a train on that control section; and each im ulse device 7 relay ofthe corresponding control section for governing said I sively inaccordance with traflic conditions in the corresponding block sectionand in the next blocksection in ad In an automatic train controlsystem,"

in combination; a. track divided 'intotrack circuit block sections andcomparatively short control sections, one at the entrance to each blocksection; an impulse device associated with each block section; arelaycircuit controlling devices of the corcorresponding impulse system,

means associated with and-controlled by the trolled by the relay of, th

in: nlse device succesdevice in a controlling condition I section and asource of current connected to each control section and constitutingmeans for detecting the presence of a train thereon; a controllingcircuit for each impulse de vice governed by the track circuit ofthecorrcsponding block section; a second controlling circuit for eachimpulse device governed by the relay of the control section next inadvance and also by the track circuit of the block section next inadvance; and means associated with each im ulse device and controlled bythe relay of the corresponding control section for connecting the firstcontrol circuit to that impulse device prior to the entrance of a traininto said corresponding control section and for connecting the secondcontrol circuit to that impulse device after a train enters saidcorresponding control section and so long as any part of such trainremains on that control section.

8. In an automatic train control system, in combination: a track dividedinto track circuit block sections; a comparatively short control sectionat the entrance to each block section; a relay and a source of currentconnected to each control section and constituting means for detectingthe presence of a train thereon; an insulated ramp located at theentrance to each block section; a partial circuit for normallyenergizing each ramp controlled by the track circuit of thecorresponding block section; a second partial circuit associated. witheach ramp and controlled by the track circuit of the block sec- 100 tionnext in advance; and means controlled by the relay of each controlsection for disconnecting he corresponding ramp from its first partialcircuit and connecting it to its second partial circuit when a trainenters 105 that control section and so long as any part remains on thatcontrol secof such train tion. 1

9. In an automatic train control system, in combination; a track dividedinto track circuit, block sections; a comparatively short controlsection at the entrance to each'block section; a i'elay an-d a source ofcurrent connected to each control section and constituting means forrletectin the presence'of a train thereon; an impu se device attheentrance to; each block section; vand means itssociated with eachimpulse device and conc corresponding: control section for maintainingsaid impulse while-any part of a passing train occupies said'control.section in accordance with thepresence or absence of another ,traininthelnczktrcontrol section or the next block SQClIi HIiIYE-dVaIICQ. 10.In anautomatic traitij control system, in combinationratrack; dividedinto track circuit block 5a comparatively short control sectionattheentrance to each block a-ramp at the entrance to each block section;means associated with each ramp and controlled by the corrcs )ondingcontrol.

section and corresponding b ock section for establishing a difi'erenceof potential between said ramp and a track rail when neither saidcontrol section or said block section is occupied; other meansassociated with each ramp and controlled by the control section andblock section next in ad- 10 Vance for establishing a difference ofpotential between said ramp and a tl ack rail when neither that controlsection or that block section is occupied; a vehicle adapted to travelover said truck; automatic train control apparatus on the vehicle; andmeans on the vehicle responsive to the existence of a difference ofpotential between a ramp and :1 track rail for controlling saidapparatus.

OSCAR A. ROSS.

